1. Field of the Invention
The present invention relates to a high gain antenna and wireless device using the same, and more particularly, to a high gain antenna and wireless device using the same utilizing a parallel reflection metal sheet plus vertical reflection metal sheets to form a three dimensional reflector, to increase antenna directivity and enhance antenna gain.
2. Description of the Prior Art
Antenna design is crucial to a portable device with wireless communication function, such as wireless local area network (WLAN) or other mobile communication systems. Take WLAN as an example, the antenna for an access point (AP) is usually an Omni-antenna to service stations (STA) within a certain space. Therefore, a high gain antenna at the STA helps to receive the signal from AP. Moreover, in the case when an AP uses a smart antenna, a high gain antenna will also help to improve the efficiency.
Please refer to FIG. 1, which is a schematic diagram of a conventional dipole antenna 10 and a corresponding radiation pattern RP1. As shown in FIG. 1, the dipole antenna 10 has the omni directional radiation pattern RP1 in a y-z plane, and only has an antenna gain of 2 dBi, which is not enough for some applications requiring high antenna gain.
Under such a situation, a parallel metal reflection sheet is often added behind an antenna to increase antenna directivity and enhance antenna gain. For example, please refer to FIG. 2, which is a schematic diagram of a conventional dipole antenna 20 with a parallel metal reflection sheet 22 and a corresponding radiation pattern RP2. As shown in FIG. 2, the parallel metal reflection sheet 22 is added behind the dipole antenna 20 (−y direction). Therefore, the parallel metal reflection sheet 22 reflects radiation of the dipole antenna 20 in the −y direction toward the +y direction, and also narrows half power beamwidth in an x-y plane. As a result, an antenna gain increases to 4-5 dBi.
However, an antenna gain of 4-5 dBi derived by utilizing the parallel metal reflection sheet is not enough, and thus the prior art needs to add a parallel metal reflection sheet with large area, which requires more space and affects input impedance. Thus, there is a need to improve over the prior art.